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This paper aims to present and discuss simplified models to estimate the measurement uncertainty when determining circularity and cylindricity deviations using coordinate measuring machines (CMM). The work was carried out according to the following steps: (i) analysis of the known Standards and documents used for uncertainty determination; (ii) analysis of the measurement system (CMM), identifying...
In this study, entropy generation effects in three-dimensional flow and heat transfer of an electrically conducting fluid over a stretching sheet have been investigated. The effects of viscous dissipation are also taken into consideration. The partial differential equations that govern the flow and thermal fields are transformed into non-linear ordinary differential equations by using suitable similarity...
This paper revisits the notorious Dean’s drive, aiming at causing unidirectional motion when attached to an object at rest (inertial propulsion). Instead of the usual circular path along which lumped eccentric masses move, a novel figure-eight-shaped curve is proposed. It is generally shown that the rotational kinetic energy accumulated in the rotating masses produces an equivalent linear ‘initial’...
In this paper, a PEM fuel cell hybrid vehicle performance is studied. Main components of this hybrid vehicle are: fuel cell power system, DC–DC converter, battery, electric motor and transmission system. The fuel cell power system which is comprised of fuel cell stack and auxiliary components are modeled and simulated in a previous paper by the authors. The fuel cell is controlled so that it operates...
This work analyzes procedures to monitor fatigue crack propagation in smooth specimens made of high-strength structural steel based on the measurement of variations in the induced moment at the fixed support. Bending fatigue tests were performed with strain control for eight different levels of strain amplitude. The moment at the support was recorded during each test and the number of cycles to fracture...
Within important wire electrical discharge machining (WEDM) performance parameters, the discharge energy is a key factor influencing the workpiece material removal rate and surface integrity characteristics. Thus, the monitoring of electric voltage and discharge current waveforms in real situations of WED-Machining is a suitable method to the evaluation and control of process behavior. In this paper,...
The authors developed a model of a three-dimensional compression test at 135° of a maxillary canine tooth endodontically treated with human and bovine dentin posts and validated it with data from literature. A three-dimensional model of a canine tooth treated endodontically was built with composite resin, cement and periodontal ligament. Simulations of compression tests were performed to validate...
Thermally fully developed mixed convection flow of nanofluids in a vertical annular pipe was investigated. Because of the non-adherence of the fluid–solid interface in the presence of nanoparticles, known as slip condition, the Navier’s slip condition was considered at the pipe walls. The Buongiorno’s model was employed for nanofluids that incorporate the effects of Brownian motion Nb and thermophoresis...
The purpose of this paper is to present two methodologies, one being analytic in nature and the other computational, both with the objective of producing a diagnostic of the electromagnetic forces, along with the electromechanical stresses which occur in transformers due to inrush and short circuit currents. To reach the desired outcome, a computational model was developed using the finite element...
Many theoretical and experimental studies have been carried out in order to develop autonomous robots to travel along telecommunication lines and power transmission lines to perform inspection and/or repair work. These robots can improve the efficiency, reduce labor and are expected to reduce the risks of accident of maintenance personnel. In spite of theoretical researches and technological developments...
The aim is to study the influence of the cutting conditions in the lives of drills used in dental implantology, when bovine tibia is used as work material. The input variables were the cutting tool materials (tetragonal zirconia polycristals ceramic and martensitic stainless steel) both uncoated, the feed velocity (24 and 45 mm/min) and the spindle speed (1,000 and 2,500 rpm). The output variables...
In this work, two complex-shaped products have been reverse engineered through rapid prototyping (RP). First product is a single unit with a number of complex features while the second product has sub-parts to be assembled together. These sub-parts have various complexities. One sub-part will frequently be in motion. Target points are set on complex features of the scanned 3D point data to measure...
A novel type of three-way diffuser/nozzle element of valveless piezoelectric micropump is presented, and an orthogonal design of the tube is done by computational fluid dynamics. Comparison of the simulation results between the traditional diffuser/nozzle element and the three-way diffuser/nozzle element shows that the latter has a better performance. The λ defined as the ratio of the total pressure...
Most of the vibration problems in vertical washing machines occur during the water extraction process (spinning stage), when high unbalance forces act on the system. The unbalance forces result from the combination of high rotating velocities and the uneven, and unpredictable, mass distribution of the clothing in the machine basket. Hence, reducing system response to unbalance is a way of improving...
This work deals with the implementation of a position and orientation automatic control of an underwater vehicle to perform inspection tasks of submerged structures without using the knowledge of a previous dynamic model in the control law and, mainly, by using a low-cost embedded minimal instrumentation. This instrumentation does not employ expensive components to determine the position and orientation...
This paper analyzes the steady, mixed convection heat and mass transfer along a semi-infinite vertical plate with variable heat and mass fluxes embedded in a doubly stratified micropolar fluid. A uniform magnetic field of magnitude $$B_0$$ B 0 is applied normal to the plate. The governing nonlinear partial differential equations are transformed into a system of coupled nonlinear ordinary...
The study of natural convection in triangular enclosures has many practical applications. In this paper, natural convection heat transfer inside triangular cavities with two different right-angle positions is studied numerically by the second-order lattice Boltzmann method. The effects of Rayleigh number and geometrical parameters of the cavity on the flow field and heat transfer for various base...
This article looks at the mixed convection flow of an Oldroyd-B fluid bounded by a porous stretching surface. Mathematical formulation is developed in the presence of heat source and power law heat flux. Velocity and temperature are computed. Plots for different parameters are analyzed. Numerical values of skin friction coefficient are examined.
The paper analyzes the effect of hydrodynamic viscous boundary layer growth over the performance of a thermal storage tank during the discharge cycle. As well established in Fluid Mechanics textbooks, a viscous boundary layer modifies the velocity profile across the tank section. Consequently, in a discharge cycle the warm water flowing outside the boundary layer (i.e., in the core region) reaches...
In this paper, two approaches are investigated to enhance the heat transfer coefficient in VVER-440 fuel rod bundle. The first approach is the use of nanofluids as the coolant media and the second approach is putting mixer vanes on the spacer grids. The fuel rod bundle contains 60 fuel rods with length of 960 mm and 4 spacer grids. To perform correct calculation the grid quality of fuel rod bundle...
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